The Electronic Structure of Perovskite Solar Cell Interfaces
Rebecka Lindblad a, Bertrand Philippe a, Håkan Rensmo a, Hans Siegbahn a, Johan Oscarsson a, Byong-wook Park b, Dongqin Bi b, Erik M. J. Johansson b, Mihaela Gorgoi c, Michael Odelius d
a Department of Physics and Astronomy, Uppsala University, Sweden, Uppsala, Sweden
b Uppsala University, Ångström Laboratory, Sweden, Lägerhyddsvägen, 1, Uppsala, Sweden
c Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Germany, Berlin, Germany
International Conference on Hybrid and Organic Photovoltaics
Proceedings of 6th International Conference on Hybrid and Organic Photovoltaics (HOPV14)
Ecublens, Switzerland, 2014 May 11th - 14th
Organizers: Michael Graetzel and Mohammad Nazeeruddin
Oral, Rebecka Lindblad, presentation 174
Publication date: 1st March 2014

Recently the use of soluble semiconductors such as organic-inorganic perovskites has shown great promise as light absorbers in solid state mesoscopic solar cells. A functioning solar cell requires well aligned energy levels in the different materials: the light absorber, the supporting mesoporous oxide and the hole conductor. A key question in the development of perovskite materials is thus the understanding of the electronic structure and energy level matching at the different interfaces. In this study, we use photoelectron spectroscopic techniques to experimentally study such properties of perovskite films deposited onto mesoporous oxides.

Photoelectron spectroscopy with hard X-rays (HAXPES) can be used to study buried interfaces in a non-destructive way. It is therefore possible to directly measure the occupied energy levels of the perovskite as well as the TiO2 buried beneath, and thereby receive a direct measurement of energy level matching of the interface. The study involves measurements of the electronic structure and chemical composition of different perovskite materials where the halide or the organic cation have been varied (for example CH3NH3PbI3 and CH3NH3PbBr3). Experimental results are also compared to theoretically calculated density of states (DOS) using density functional theory (DFT).

We show that two different deposition techniques of the TiO2/CH3NH3PbI3 interface give results indicating similar electronic structures. Especially a similar binding energy of the valence band edge gives similar energy level matching in a solar cell. Simulated DOS of the valence structure describes the experimental spectra very well and shows that the outermost levels consist of lead and iodine orbitals. Due to a relatively higher cross section at high photon energies for heavier elements, HAXPES is therefore very useful to study the position as well as the orbital character of the valence band edge. [1]



[1] R. Lindblad, D. Bi, B.-w. Park, J. Oscarsson, M. Gorgoi, H. Siegbahn, M. Odelius, E. M. J. Johansson and H. Resmo, J. Phys. Chem. Lett., http://dx.doi.org/10.1021/jz402749f
© FUNDACIO DE LA COMUNITAT VALENCIANA SCITO
We use our own and third party cookies for analysing and measuring usage of our website to improve our services. If you continue browsing, we consider accepting its use. You can check our Cookies Policy in which you will also find how to configure your web browser for the use of cookies. More info